A liquid ejecting apparatus that supplies liquid from a liquid supplying source into a liquid ejecting head is used for various kinds of liquid. An ink-jetting recording apparatus is a typical example. Then, the conventional art is explained for an ink-jetting recording as an example.
As shown in FIG. 17A, an ink-jetting recording apparatus 111 comprises: a main-body case 112 as an immobile member, a platen 113, a guide shaft 114, a carriage 115 as a movable member, a timing belt 116, a carriage motor 117, and a recording head 120 as a liquid ejecting head.
In addition, the ink-jetting recording apparatus 111 includes a pressure damper unit 121, an ink-cartridge 123 as a liquid supplying source, a pressure pump 125, and a capping apparatus 126. The pressure damper unit 121 has a function for inhibiting a pressure change of ink in a way from the ink-cartridge 123 to the recording head 120.
The main-body case 112 is a substantially rectangular parallelepiped box-like case. A cartridge holder 112a is formed at a right-hand end portion of the main-body case 112 in FIG. 17A. The platen 113 is arranged in a main-scanning direction, in which the recording head 120 reciprocally moves, in the main-body case 112. The platen 113 has a function for supporting a recording medium (not shown), which is fed by a paper feeding unit (not shown).
The guide shaft 114 is formed by a rod-like member. The guide shaft 114 is arranged in the main-body case 112, in parallel with the platen 113, that is, in the main-scanning direction. The carriage 115 is pierced through by the guide shaft 114 in a relatively movable manner, so that the carriage 115 is supported in a movable manner reciprocally in the main-scanning direction with facing the platen 113.
Then, the carriage 115 is connected to the carriage motor 117 via the timing belt 116. The carriage motor 117 is supported by the main-body case 112. When the carriage motor 117 is driven, the carriage 115 is driven via the timing belt 116. As a result, the carriage 115 moves reciprocally along the guide shaft 114.
The recording head 120 is provided at a surface of the carriage 115, facing the platen 113. The recording head 120 comprises a plurality of nozzles (not shown) for ejecting ink, as a kind of liquid, toward the platen 113.
The pressure damper unit 121 is mounted on the carriage 115. The pressure damper unit 121 stores the ink temporarily, and supplies the ink that has been temporarily stored into the recording head 120 while inhibiting a pressure change of the ink. In the shown example, two pressure damper units 121 are mounted on the carriage 115. However, the number of the pressure damper units 121 may be increased depending on the number of colors of ink or the like.
The ink cartridge 123 is contained in a removable manner in the cartridge holder 112a that is an immobile member. In the shown example, four ink cartridges 123 are arranged correspondingly to four ink colors. In FIG. 17B, a sectional view of one of the four ink cartridges 123 is shown.
As shown in FIG. 17B, the ink cartridge 123 comprises an ink case 131 and an ink pack 132. In the present example, the ink case 131 is formed in a substantially rectangular parallelepiped. In addition, the ink pack 132 is formed by two overlapped films 132a and 132b as flexible members. In the ink pack 132, the ink is sealed. The ink pack 132 has an ink-discharging port 132c. The ink pack 132 is contained in the ink case 131 in such a manner that only the ink-discharging port 132c is exposed from the ink case 131. Other portions of the ink park 132 than the ink-discharging port 132c forms an airtight state in the ink case 131. In addition, a gap 133 is formed between the ink case 131 and the ink pack 132.
In addition, the ink case 131 is provided with a communication hole (not shown) that communicates with the gap 133. When an air is introduced through the communication hole, a pressure in the gap 133 is so increased that a force capable of pressing the ink pack 132 may be generated.
The ink-discharging port 132c of the ink pack 132 is connected to the pressure damper unit 121 via an ink supplying tube 135, for each ink color, as shown in FIG. 17A. The ink supplying tube 135 forms a liquid-supplying way. Thus, when an air is introduced into the gap 133 in the ink case 131, the ink in the ink pack 132 is supplied to the pressure damper unit 121 via the ink supplying tube 135.
The pressure pump 125 is arranged above the ink cartridge 123, and is fixed to the main-body case 112. The pressure pump 125 is capable of absorbing atmospheric air and of discharging pressurized air. The pressurized air discharged from the pressure pump 125 is supplied to a pressure detecting unit 138 via a pressurizing tube 137.
In the pressure detecting unit 138, a pressure of the pressurized air supplied form the pressing pump 125 is detected. Then, based on the pressure detected in the pressure detecting unit 138, an operation of the pressing pump 125 is adjusted. Thus, the air supplied from the pressing pump 125 is adjusted within a predetermined pressure range by the pressure detecting unit 138.
The pressure detecting unit 138 is connected to the communication holes of the respective ink cartridges 123 via four air-supplying tubes 139. Thus, the air adjusted within the predetermined pressure range is introduced into the gap 133 of each ink cartridge 123.
As described above, in each ink cartridge 123, the ink pack 132 is pressed by the pressurized air supplied from the pressing pump 125, and the ink in the ink pack 132 is supplied to the pressure damper unit 121. Then, the ink is temporarily stored in the pressure damper unit 121, and the ink that has been temporarily stored is supplied into the recording head 120 while a pressure change of the ink is inhibited.
At that time, based on image data, an ink drop is ejected from the recording head 120 while the recording medium is fed by the paper-feeding unit (not shown) in a sub-scanning direction and the carriage 115 is moved by the carriage motor 117 in the main scanning direction. Thus, a printing operation onto the recording medium is conducted.
The capping unit 126 is arranged at a non-printing area (at a home position) on the reciprocating way of the carriage 115. Then, a cap 126a formed by an elastic material such as elastomer, which can come in contact with a nozzle-formed surface of the recording head 120 to seal the same, is arranged on an upper surface of the capping unit 126. On the other hand, at the capping unit 126, a straplike wiping member 126f formed by an elastic material such as rubber is provided adjacent to a portion of the cap 126a on a printing-area side.
FIG. 18 is a sectional view showing a state wherein the recording head 120 and the plurality of pressure damper units 121 are integrated via a connection member 140. FIG. 17A shows the example wherein the two pressure damper units 121 are mounted, but FIG. 18 shows an example wherein eight pressure damper units are arranged correspondingly to eight ink colors. Herein, in FIG. 18, in order to depict the numerical signs, the outlines of two pressure damper units 121 are shown by two-dot chain lines.
The pressure damper unit 121 is explained in details. A damper room 121b is formed by hallowing out a side surface of a unit substrate 121a that is a thick plate-like member. Then, on the side surface of the unit substrate 121a, an elastic sheet 121c is attached by thermal welding or the like. Although not shown in FIG. 18, the ink supplying tubes 135 shown in FIG. 17A are connected to the pressure damper units 121 so that the ink flows from the ink supplying tubes 135 into the damper rooms 121b. In addition, in the unit substrate 121a, a flowing-out way 121d is provided. One end thereof is opened to the damper room 121b, and the other end thereof is opened to a lower end portion of the unit substrate 121a. At the lower end portion of the unit substrate 121a, a downward connection tube 121e is formed.
Eight receiving hollow portions 165 are provided at an upper surface of the connection member 140, correspondingly to the eight ink colors. At a bottom part of each receiving hollow portion 165, a film-like or plate-like filter 166 is arranged in a substantially horizontal direction. An ink supplying needle 167 stands up on an upper side of the filter 166. That is, the eight filters 166 are arranged at the upper surface of the connection member 140, and axes of the respective ink supplying needles 167 are substantially perpendicular to the respective filters 166. Then, in order to set a filtration area of the filter 166 at a predetermined size, a lower portion of each ink supplying needle 167 is smoothly enlarged to become a large-diameter portion 167a. 
The connection tube 121e of the pressure damper unit 121 is inserted into the receiving hollow portion 165. At that time, an elastic sealing ring 168 is provided between the ink supplying needle 167 and an inside surface of the connection tube 121e, so that the standing posture of the pressure damper unit 121 with respect to the connection member 140 is maintained.
Eight communication ways 170 that extend from the respective filters 166 to respective ink-introducing ports 169 of the recording head 120 are formed in the connection member 140. The lengths of the communication ways 170 are dependent on distances from the respective filters 166 to the respective ink-introducing ports 169, and thus different from each other.
A control board 171 for supplying an operational signal to the recording head 120 is attached on an upper surface of a head case 105. A packing member 172 made of an elastomeric material or the like is layered on the control board 171 for an ink-sealing function. The ink from the communication ways 170 of the connection member 140 is adapted to flow into the ink-introducing ports 169 through holes 172a formed in the packing member 172 and holes 171a formed in the control board 171.
FIG. 19 is a schematically sectional view showing inside structure of the recording head 120 integrated to the connection member 140. With reference to FIG. 19, the inside structure of the recording head 120 is explained.
The recording head (ink-ejecting head) 120 is formed by joining a flow-path unit 103 and the head case 105. Nozzles 101 and pressure generating chambers 102 are formed in the flow-path unit 103. Piezoelectric vibrating members 104 as pressure generating means are contained in the head case 105.
The flow-path unit 103 is formed by laminating a nozzle plate 106, a flow-path forming plate 109, and a vibrating plate 110. The nozzle plate 106 has a nozzle-formed surface 106a in which the nozzles 101 are formed. In the flow-path forming plate 109, a space corresponding to the pressure generating chambers 102, common ink chambers 107 and ink supplying paths 108 communicating the pressure generating chambers 102 with the common ink chambers 107 is formed. The vibrating plate 110 becomes an upper wall of the pressure generating chambers 102. The nozzle-formed surface 106a is flat.
The piezoelectric vibrating member 104 contracts in a longitudinal direction thereof in a charged state, and extends in the longitudinal direction during a discharging process from the charged state, depending on a driving signal inputted thereinto. That is, the piezoelectric vibrating member 104 is so-called a vibrating member of vertical vibration mode. A tip end of the piezoelectric vibrating member 104 is fixed to an island portion 110a of the vibrating plate 110 that forms the upper wall of the pressure generating chambers 102. A base end of the piezoelectric vibrating member 104 is fixed to a base stage 118.
In addition, head flow-paths 119 are formed in the head case 105 at portions corresponding to the common ink chambers 107 in order to introduce the inks from the ink cartridges 123 to the common ink chambers 107. The entrance portion of each head flow path 119 forms the ink-introducing port 169. A circular protrusion 122 is formed at an opening edge of each head flow-path 119.
In the recording head 120, in accordance with contraction/extension of the piezoelectric vibrating member 104, the pressure generating chamber 102 expands/contracts. Thus, a pressure change of the ink is caused in the pressure generating chamber 102, so that suction of an ink meniscus and ejection of an ink drop are carried out. As shown in FIG. 19, a flexible cable 124 for inputting a driving signal in the piezoelectric vibrating member 104 extends from the control board 171 to the piezoelectric vibrating member 104. An end portion of the control board 171 is provided with a connector 173. A control signal from a computer unit, which controls the whole ink-jetting recording apparatus 111, is adapted to be inputted to the connector 173.
In the recording head 120, in a direction perpendicular to the paper of FIG. 19, the piezoelectric vibrating members 104, the pressure generating chambers 102 and the nozzles 101 are arranged in line. That is, in the nozzle plate 106, two rows of nozzles 101a are formed in line. Then, the recording medium (recording paper) is supported by the platen 113 shown in FIG. 17A, and the nozzle-formed surface 106a of the recording head 120 is adapted to face the recording medium with a predetermined gap.